tasks a-s

Task/Brownian-tree/Java/brownian-tree.java

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+import java.awt.Graphics;
+import java.awt.image.BufferedImage;
+import java.util.*;
+import javax.swing.JFrame;
+
+public class BrownianTree extends JFrame implements Runnable {
+
+    BufferedImage I;
+    private List<Particle> particles;
+    static Random rand = new Random();
+
+    public BrownianTree() {
+        super("Brownian Tree");
+        setBounds(100, 100, 400, 300);
+        setDefaultCloseOperation(EXIT_ON_CLOSE);
+        I = new BufferedImage(getWidth(), getHeight(), BufferedImage.TYPE_INT_RGB);
+        I.setRGB(I.getWidth() / 2, I.getHeight() / 2, 0xff00);
+        particles = new LinkedList<Particle>();
+    }
+
+    @Override
+    public void paint(Graphics g) {
+        g.drawImage(I, 0, 0, this);
+    }
+
+    public void run() {
+        for (int i = 0; i < 20000; i++) {
+            particles.add(new Particle());
+        }
+        while (!particles.isEmpty()) {
+            for (Iterator<Particle> it = particles.iterator(); it.hasNext();) {
+                if (it.next().move()) {
+                    it.remove();
+                }
+            }
+            repaint();
+        }
+    }
+
+    public static void main(String[] args) {
+        BrownianTree b = new BrownianTree();
+        b.setVisible(true);
+        new Thread(b).start();
+    }
+
+    private class Particle {
+
+        private int x, y;
+
+        private Particle() {
+            x = rand.nextInt(I.getWidth());
+            y = rand.nextInt(I.getHeight());
+        }
+
+        /* returns true if either out of bounds or collided with tree */
+        private boolean move() {
+            int dx = rand.nextInt(3) - 1;
+            int dy = rand.nextInt(3) - 1;
+            if ((x + dx < 0) || (y + dy < 0)
+                    || (y + dy >= I.getHeight()) || (x + dx >= I.getWidth())) {
+                return true;
+            }
+            x += dx;
+            y += dy;
+            if ((I.getRGB(x, y) & 0xff00) == 0xff00) {
+                I.setRGB(x - dx, y - dy, 0xff00);
+                return true;
+            }
+            return false;
+        }
+    }
+}